Egg farmers say free range farms are much more susceptible to bird flu and that cannot be ignored in any discussion of new national free range protocols.

Bede Burke, chairman of the New South Wales Farmers Association Egg Committee, says biosecurity has to be included in discussion about defining free range.

"How can it be left out? How can we leave out the potential exposure to the exotic disease that we have eradicated once?" Mr Burke asked.

"Bird flu has made many free range producers very nervous.

"We have had no growth in the cage sector, which is 60 per cent of the industry, but if free range investment continues, all of these new, free range farms, will be much more exposed to a risk of bird flu."

"We should not forget the devastation caused to the industry and the destruction of nearly half a million avian flu infected birds, at two egg farms near Young late last year."

Those bird flu outbreaks at Young were traced to wild ducks having contact with chickens and was reported to have severely reduced the supply of eggs into the Australian market, in the lead up to Christmas.

Another case of bird flu on a free range farm in the Hunter Valley in 2012, was also traced to wild ducks.